Various types of taut-wire protective fences are known in the patent literature and in the marketplace. Simply described, taut wire protective fences incorporate tensioned wires which are connected to sensors. These sensors provide an alarm indication of an attempt to climb or cut the fence. U.S. Pat. Nos. 3,634,638 and 3,912,893, owned by applicants, described sensors which are particularly suited for taut wire fence applications and which have found wide market acceptance.
There is described and claimed in applicant's Published UK Patent Application No. (2416) a sensor for taut wire fence systems which has a pair of terminals, each connected to a different taut wire such that predetermined relative motion between the first and second connection terminals produces an electrical connection between first and second electrical contacts, resulting in an alarm indication.
There are also known a variety of security barriers which employ a fiber optics sensing apparatus. U.K. Published Patent Application No. 2,098,770 describes a security barrier structure comprising a lattice of hollow tubular members through which fiber optic cable is threaded. An attempt to break through the barrier breaks or distorts the fiber by overtensioning same, thus causing a sensible attenuation of an optical signal transmitted through the cable.
U.K. Published Patent Application Nos. 2,038,060; 2,046,971 and 2,062,321 and U.S. Pat. Nos. 4,292,628 and 4,399,430 all show security applications, wherein an alarm indication is provided by breakage of an optical fiber. U.K. Published Patent Application No. 2,077,471 shows a security application wherein a pressure sensitive fiber optic composite cable is provided. Israel Pat. No. 66520 describes an intrusion warning wire fence comprising an outer core and an inner coaxial optical fiber.